I thought up a simple solution for countersinking chassis elements that come in hard-to-assemble shapes: I covered the front with 3 mm-thick cork boards. The following pictures show the individual steps, as usual﻿.

Before the start of the gluing process, the cork boards have to be cut to size for the front. Since they will eventually need to be flush with the sides, they are used as a guide when gluing on the front and then removed.

I will skip the description of the assembly process here and just show the most important steps﻿.

Once the boxes have been sanded, cut and sprayed with granite-effect paint, I use a brush to coat the front with wood glue; then the cork board is inserted.

The chassis cutouts are opened up with the box cutter and the speakers are put in. Always drill holes before putting in the screws﻿!

With the sharp blade of the knife, slowly and carefully (!) cut around the tweeter. The cutout for the bass is already finished. Now both chassis elements are sitting flush in the front piece﻿.